The invention concerns an incorporated lighting system in furniture with a preferably cylindrical outer housing for incorporation in a vertically perforated ceiling or in the cover of a piece of furniture. Incorporated lighting systems in furniture of the given type have a concavely shaped reflector radiating downward, in which a halogen lamp with a laterally mounted base, or the like, is arranged in a horizontally flat-lying manner. Such lighting systems (projection lamps) are known. A construction with small height space! for incorporation results due to the flat-lying halogen lamp arranged horizontally in the reflector. These lights are therefore incorporated in the ceiling or in the cover of a piece of furniture, for example, in the trim, piece of a cabinet projecting toward the front; the doors of the cabinet open underneath the lighting system. The problem results that there is a heat load of the upper edges of the doors, if these are directly under the lighting system. For this case, various mechanical and/or electronic circuit breakers have been made known, which will prevent an inadmissible heat load of the upper edges of the doors by switching off the projection lamp. In practice, however, it is too expensive, since the mounting of such circuit breaker devices must be produced in addition to the incorporation of the lighting system.
The task of the invention is to develop an incorporated lighting system in furniture of the given type, which exercises only a very small heat load on the irradiated object with a pregiven light flux (luminous intensity), so that, e.g., with the use of a lighting system directly above a door on a piece of furniture, no additional means are necessary for switching off the illumination and/or no other heat protection measures are necessary for the upper edges of the doors.
This task is resolved according to the present invention, in that the concave reflector has an apical opening in the region of its apex.
Inside the reflector, and in fact underneath this apical opening, there is found the horizontally flat-lying halogen lamp, which is fitted to the apical opening more or less, with an appropriate selection of the shape and size of the apical opening. It is thus essential that the backward fraction of heat radiation produced by the illumination means can leave the inside space of the reflector toward the top and is not contained in the light beam in the previously known way, which the radiator emits downward.
Such reflectors with apical opening may be, for example, aluminum reflectors or metallized reflectors. A particularly advantageous form of embodiment of the invention is provided in that a cold-light reflector with apical opening is used. Cold-light reflectors of the known structural type possess a special infrared-transparent coating of the reflector, which transmits toward the outside approximately 60% of the infrared component in the light, and thus the heat radiation in the irradiated light beam is reduced. In combination with the apical opening, which allows the back portion of the heat radiation produced by the lighting means to escape almost completely from the inside space of the reflector, an extremely high reduction of heat radiation will be achieved in the emitted light beam.
Another improvement of the present invention is that the emitted light beam is also covered by an IR blocking filter disk. Two IR blocking filter disks, arranged at a distance as in window-insulating glass disks, appropriately reinforce the filter effect.
The structural control of the heat radiation yielded from the new reflector with apical opening requires special measures, particularly since lighting systems incorporated into furniture must fulfill increased safety specifications and such furniture is often made of plastic. As another feature of the invention, it is thus proposed that a heat distribution plate is arranged essentially horizontally at a distance above the apical opening.
This heat distribution plate should absorb as high a fraction as possible of the heat radiation impinging on it and therefore it is appropriate to design the apical opening of the surface of the heat distribution plate turned toward the reflector in an absorbing manner, for example, to blacken this surface. This also has the advantage that the heat distribution plate blocks light transmission through air vents at the top of the outer housing.
This heat distribution plate is preferably mounted on spacers in such a way that the heat distribution plate is ventilated with air. The heat distribution should be produced on surfaces that are air-ventilated as much as possible. This improves the heat transfer to the air. On the other hand, heat conduction in the material of the heat distribution plate should be reduced throughout in order that mounting with the spacers, which are for the most part made only of plastic, do not produce with temperature loads that are too high. The applicant has obtained excellent results with heat distribution plates of mica.
With respect to the considerable heat radiation, which a cold-light reflector emits to the outside particularly by the reflector wall and which could endanger the adjacent furniture parts with the incorporation of such lighting systems in furniture in the desired minimal space, a lighting system of the invention is provided with a special shield, which is characterized by the fact that the reflector is immersed partially or nearly completely from the top into an inside housing, which surrounds the reflector like a sleeve and is arranged at a distance to the reflector as well as to the outer housing, which clearly makes difficult the heat exchange between inner and outer housing.
This measure, as also the effective air ventilation of the heat distribution plate, is improved by the fact that the distance between the outer housing and the inner housing and/or the distance between the inner housing and the lower part of the reflector is formed by a air-guidance channel with a lower light-input opening and an upper light-output opening, and that air vents are provided at the top of the outer housing.
The technical heat advantages of the features presented above of the new lighting system are of considerable importance. They are persuasive solutions to the established task, both as individual features as well as in combinations (see the formulations given there). However, the combination effect of the features must be underscored as particularly astounding and not predictable for the expert. The combination of these features reduces the heat load of an irradiated object so decisively in the case of the new lighting system with the standard luminous intensity for household use that the object, for example, the upper door edge of a door to a piece of furniture, can be introduced a few millimeters from the light and can be left there for a period of time without heat damage to the object. This combination claimed as a particular invention is characterized by the fact that a cold-light reflector is used as the reflector, that the reflector has an apical opening in the region of its apex, and that a heat distribution plate ventilated by air and absorbing the heat radiation is arranged essentially horizontally at a distance above the apical opening.
The new reflector with apical opening also has considerable advantages for changing the halogen lamps. In the standard case, accessibility from below and the manipulation of a halogen lamp in the relatively small inside space of the reflector is very limited. These disadvantages are resolved in the solution of the invention in that the halogen lamp is held by means of a lamp socket, which is mounted on the outer housing, and that the apical opening of the reflector has a shape and size corresponding to the outer contour of the lamp and socket, such that the reflector can be removed downward from above the lamp and socket, which are stationary in position. The halogen lamp is then freely accessible and sufficient space is present in the outer housing, in order to make possible without problem the exchange of the halogen lamp by the final consumer.